can we walk in to a genius bar

I can only give my experience, which is yes, no, or maybe.

I’ve walked into an Apple Store and got Genius Bar help immediately without an appointment because it wasn’t busy at all. I mean - it was as busy as a Microsoft Store. I went in to a super busy Apple Store, talked to check-in, waited patiently and got service just waiting there. I still wasn‘t sure they were going to do anything until my wife’s iPhone was handed over. And once I was told flatly no, but that I could come in first thing in the morning to be placed on the daily waiting list.

If you’re in a hurry, finding an appointment at another store or getting on the daily waitnt list might be your best options.

Genius Bars are usually busy. And it depends at what store. If you walk in without an appointment you might not get service as it might depend if there are cancellations or no shows.

But don't count on it.

The two Apple stores near me typically are very busy and fully booked with appointments. So walk-ins may well find they cannot get service or may have to wait around for hours to catch a break in the line of those with appointments.

Best to make an appointment to ensure you get help when you show up.

your post seem to be missing info

as to why Wednesday would be a thing